More active analgesic combinations are in constant demand because they offer the attractive possibility of relieving pain with reduced dosages thereby diminishing the expected side effects and toxicity that would result from the otherwise required higher dosages.
U.S. Pat. No. 3,393,197, issued to Pachter and Matossian on July 16, 1968, discloses N-substituted-14-hydroxydihydronormorphines, including the N-cyclobutylmethyl derivative, commonly called nalbuphine: ##STR1## Pachter and Matossian and others, such as H. W. Elliott, et al., J. Med. (Basel), 1, 74-89 (1970); H. Blumberg, et al., Pharmacologist, 10, 189 (Fall 1968); P. Roberts, Drugs of the Future, 2, 613-5 (1977), disclose the use of nalbuphine as an analgesic for the control of moderate to severe pain.
U.S. Pat. No. 4,237,140, issued to J. R. Dudzinski on Dec. 2, 1980, describes an analgesic mixture of nalbuphine and acetaminophen. U.S. Pat. No. 4,282,215, issued to J. R. Dudzinski and W. K. Schmidt on Aug. 4, 1981, describes an analgesic mixture of nalbuphine and aspirin.
U.S. Pat. Nos. 3,228,831 and 3,385,886 issued to Nicholson and Adams disclose the synthesis, formulation, and analgesic properties of .alpha.-methyl-4-(2-methylpropyl)benzeneacetic acid, commonly called ibuprofen: ##STR2## Adams et al., Arch. Pharmacodyn. Ther., 178, 115 (1969), further characterize the use of ibuprofen as an analgesic.